It says on the army jobs website that some of the Royal Signal job trade's offer promotion after phase 2 training, my question is whats the chances of being promoted straight to a Lcpl after phase 2 (trade: Comms Sys Engineer)

pretty good if you are a good boy. You will still have to do a junior leadership course though (cant remember what they call it exactly as it is still a relatively recent change (last 18 months I think)) and I think you do that before you leave Phase 2.